45 research outputs found
Single-photon quantum nonlocality: Violation of the Clauser-Horne-Shimony-Holt inequality using feasible measurement setups
We investigate quantum nonlocality of a single-photon entangled state under
feasible measurement techniques consisting of on-off and homodyne detections
along with unitary operations of displacement and squeezing. We test for a
potential violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, in
which each of the bipartite party has a freedom to choose between 2 measurement
settings, each measurement yielding a binary outcome. We find that
single-photon quantum nonlocality can be detected when two or less of the 4
total measurements are carried out by homodyne detection. The largest violation
of the CHSH inequality is obtained when all four measurements are
squeezed-and-displaced on-off detections. We test robustness of violations
against imperfections in on-off detectors and single-photon sources, finding
that the squeezed-and-displaced measurement schemes perform better than the
displacement-only measurement schemes.Comment: 7+ pages, 7 figures, 1 table, close to published versio
Detecting the degree of macroscopic quantumness using an overlap measurement
We investigate how to experimentally detect a recently proposed measure to
quantify macroscopic quantum superpositions [Phys. Rev. Lett. 106, 220401
(2011)], namely, "macroscopic quantumness" . Schemes based on
overlap measurements for harmonic oscillator states and for qubit states are
extensively investigated. Effects of detection inefficiency and coarse-graining
are analyzed in order to assess feasibility of the schemes.Comment: 12 pages, 8 figures, to be published in J. Opt. Soc. Am.
Probing the effects of interaction in Anderson localization using linear photonic lattices
We show how two-dimensional waveguide arrays can be used to probe the effect
of on-site interaction on Anderson localization of two interacting bosons in
one dimension. It is shown that classical light and linear elements are
sufficient to experimentally probe the interplay between interaction and
disorder in this setting. For experimental relevance, we evaluate the
participation ratio and the intensity correlation function as measures of
localization for two types of disorder (diagonal and off-diagonal), for two
types of interaction (repulsive and attractive), and for a variety of initial
input states. Employing a commonly used set of initial states, we show that the
effect of interaction on Anderson localization is strongly dependent on the
type of disorder and initial conditions, but is independent of whether the
interaction is repulsive or attractive. We then analyze a certain type of
entangled input state where the type of interaction is relevant and discuss how
it can be naturally implemented in waveguide arrays. We conclude by laying out
the details of the two-dimensional photonic lattice implementation including
the required parameter regime.Comment: 5 pages, 5 figure
Robust-to-loss entanglement generation using a quantum plasmonic nanoparticle array
We introduce a scheme for generating entanglement between two quantum dots
using a plasmonic waveguide made from an array of metal nanoparticles. We show
that the scheme is robust to loss, enabling it to work over long distance
plasmonic nanoparticle arrays, as well as in the presence of other
imperfections such as the detuning of the energy levels of the quantum dots.
The scheme represents an alternative strategy to the previously introduced
dissipative driven schemes for generating entanglement in plasmonic systems.
Here, the entanglement is generated by using dipole-induced interference
effects and detection-based postselection. Thus, contrary to the widely held
view that loss is major problem for quantum plasmonic systems, we provide a
robust-to-loss entanglement generation scheme that could be used as a versatile
building block for quantum state engineering and control at the nanoscale.Comment: 32 pages, 11 figure